This invention relates to information display signs or devices of the general type illustrated in U.S. Pat. No. 3,562,938 to Salam, granted Feb. 16, 1971. Such devices basically comprise a panel having a plurality of discrete light-transmitting areas arranged along transversely spaced upright columns and surrounded by a background which is perferably, but not essentially, opaque. The panel is normally backlighted and the desired display is usually viewed as light transmitted through the discrete areas. Circular discs are mounted behind the panel for planar movement of each disc between a first position overlying a light-transmitting area and a second position clear of such area. By arranging the individual discs in one or the other of such positions, any desired pattern of light transmission can be achieved through the individual light-transmitting areas, thereby producing the desired visual pattern on the viewed panel.
Prior structures pertaining to this type of display have typically utilized multiple layers of material to produce individual retaining cells surrounding each disc. The laminated struture produced by these layers presents substantial fabrication problems relating to choice of materials, material compatability between the various layers and the discs, surface irregularities produced during stamping of various layers, and adhesive problems encountered in bonding the various layers to one another. These difficulties become even more pronounced when attempting to fabricate such a display sign for exterior use, where temperature fluctuations, wind loads and structural design elements reach substantial magnitudes.
The present alternative panel structure was devised in an attempt to simplify fabrication, while simultaneously providing structural reinforcement in the panel itself. The improvement further reduces or completely eliminates the need for use of adhesive to produce a sandwiched panel structure.
Other patents relating to this general type of display are U.S. Pats. Nos. 3,685,040, 3,601,914 and 3,659,366. They are illustrative of prior attempts to fabricate this general type of display by laminating successive sheets of materials to one another.
According to this disclosure, the movable discs rest upon discrete projections formed between the panel and a backing member. The projections are arranged along upright columns and transverse lines. The spacing between the projections adjacent to one another in each line is less than the diameter of the discs, so that the discs can rest in a bridging position supported by two adjacent projections. The upright spacing between parallel projections in one column is greater than the disc diameter, while the corresponding upright spacing between projections in the laterally adjacent columns is less than the diameter of the discs. Therefore, the disc can be moved over the projection on which it rests in the one column, but cannot pass between the projections in the adjacent columns. Each disc is therefore accurately supported in two stable positions and is restricted in its movement to assure its proper position either overlying a light-transmitting area of the panel, or clear of such area.